Insert for light feed, light depth of cut

Abstract

A polygonal lay down indexable cutting insert for a centrally located island and light feed and light depth of cut applications. The insert has a variable land surface angle which is 14° at each corner of the insert and merges into a 12° as measured along the flanks of the insert. A second descending angle is 27° along the flanks. The corners are radiused along the variable land surface and the descending angle surfaces to impart better strength and cutting for the insert. Moreover, the first variable descending angle is greater than the first variable descending angle along the flanks of the insert.

We claim: 
     
       1. A polygonal lay down indexable cutting insert for light feed and light depth of cut applications, comprising: (a) a top surface having a centrally located raised island having nose portions at each corner separated by inversely arcuate side regions;   (b) a bottom surface substantially parallel to said top surface, said bottom having a centrally located raised island of the same shape as the island on the top surface;   (c) a sidewall extending substantially unbroken between said top and bottom surfaces to define a body; said sidewall comprised of a plurality of component side flanks which extend from corner to corner of the polygonal insert;   (d) a cutting surface formed by the outer periphery of each of the top and bottom surfaces and comprising a cutting edge at the meeting of each component side flank and the top and bottom surfaces; said cutting edge having the shape of a descending arc as measured from each corner to each adjacent corner of the insert; said cutting surface further comprising; a variable width land surface extending rearwardly from said cutting edge; said land surface radiused at each corner of the insert and of narrower width at the corners than along the flanks of the insert body; said land surface having a variable first descending land angle; said land angle being greater at each corner than along the side flanks;   (e) a groove width surface; said land surface further having a variable second descending land angle adjacent to and rearward of said first variable land angle along the sidewall; said secondary variable land angle extending toward the groove width surface; said first and second variable land angles having surface portion radiused at each corner of the insert body; said groove width surface having a variable width along each flank of the insert body and being narrower at each corner of the insert than at the flanks of the insert;   (f) a radiused arc surface at each corner of the insert, rearward of said first descending land surface;   (g) a chip deceleration pad located at each inversely arcuate side region of the island; said pad and island sharing a first variable width ascending angle surface rising from the groove width surface to the deceleration pad and the nose portions of the island; and a second variable width ascending angle surface rising from the deceleration pad to the surface of the centrally raised island.   
     
     
       2. The insert of claim 1, further equipped with a centrally located aperture extending at least partially through the insert body from the top surface to the bottom surface. 
     
     
       3. The insert of claim 1, wherein said first variable land angle is 14° at each corner of the insert and 12° along the flanks of the insert. 
     
     
       4. The insert of claim 1, wherein the cutting edge descends from each corner portion to the mid-point of each flank from about 0.01 inches to 0.012 inches. 
     
     
       5. The insert of claim 1, wherein said feed is about 0.006 inches to 0.018 IPR and said depth of cut is 0.010 inches to 0.125 inches. 
     
     
       6. The insert of claim 1, wherein said first variable descending angle is a positive, rake angle. 
     
     
       7. The insert of claim 1, wherein the second variable descending land angle is 27° along the flanks. 
     
     
       8. The insert of claim 1, wherein said radiused arc is preferably about 0.025 inches.